1.Tìm x, biết:

a.\(\frac{1}{2}\)x\(x\)+\(\frac{2}{3}\)=\(\frac{5}{2}\)

b.\(\frac{x}{12}\)+\(\frac{5}{24}\)=\(\frac{5}{6}\)

c.(1234+\(x\)+766)x0,25=6,2:0,01

2.Tính bằng cách hợp lý.

A=\(\frac{1}{2}\)x\(\frac{5}{7}\)+\(\frac{9}{7}\)x0,3+\(\frac{1}{2}\)x\(\frac{4}{7}\)+\(\frac{9}{4}\)+\(\frac{9}{7}\)x0.2

B=\(\frac{2002\cdot15-1}{2001+2002\cdot14}\)

1.Tìm x, biết:

a.\(\frac{1}{2}\)x\(x\)+\(\frac{2}{3}\)=\(\frac{5}{2}\)

b.\(\frac{x}{12}\)+\(\frac{5}{24}\)=\(\frac{5}{6}\)

c.(1234+\(x\)+766)x0,25=6,2:0,01

2.Tính bằng cách hợp lý.

A=\(\frac{1}{2}\)x\(\frac{5}{7}\)+\(\frac{9}{7}\)x0,3+\(\frac{1}{2}\)x\(\frac{4}{7}\)+\(\frac{9}{4}\)+\(\frac{9}{7}\)x0.2

B=\(\frac{2002\cdot15-1}{2001+2002\cdot14}\)

1, tính nhanh

\(a,13\)x\(3\)x  \(32,27+67,63\)x   \(39\)

\(b,\left(1-\frac{1}{2}\right)\)x   \(\left(1-\frac{1}{3}\right)\)x   \(\left(1-\frac{1}{4}\right)\)x   \(...............\)x    \(\left(1-\frac{1}{100}\right)\)

\(c,\frac{3}{5}+25-\frac{1}{5}\)

2, tìm  \(x\)

\(a,12:x+5=3+25:5\)

\(b,170-5\)x   \(\left(x+19\right)\)\(=50\)

\(c,11\)x   \(\left(x-6\right)\)\(=4\)x   \(x+11\)

3,không thực hiện phép tính hãy giải thích kết quả của phép tính đúng hay sai

\(\left(2+4+6+......+100\right)\)\(-\left(13+15+17+.......+93\right)\)\(=40\)

Tính:

a) ( 1- \(\frac{1}{2}\)) x (1- \(\frac{1}{3}\)) x (1- \(\frac{1}{4}\)) x (1- \(\frac{1}{5}\)) x..........x ( 1- \(\frac{1}{99}\))x ( 1- \(\frac{1}{100}\))

b) ( ( 1+ \(\frac{1}{2}\)) x (1+ \(\frac{1}{3}\)) x (1+ \(\frac{1}{4}\)) x (1+ \(\frac{1}{5}\)) x..........x ( 1+ \(\frac{1}{99}\))x ( 1+ \(\frac{1}{100}\))